Science solves many years of puzzles: the genetic mechanism that coordinates the maturation of phloem cells

Studies have found that a tiny area on the root tip is responsible for coordinating the growth and development of a complex network of vascular tissues that transport sugar through the roots of plants

In a paper published in the journal Science, an international team of scientists proposed a detailed blueprint for how plants build phloem cells (the part of the tissue responsible for transporting and accumulating plant sugar and starch).

This key study revealed how the signals in the root meristem coordinate the different maturation stages of the phloem tissue

Phloem is a highly specialized vascular tissue that forms a continuous and interconnected network throughout the plant

Therefore, the phloem is the center of plant function

How do plants build "sugar lanes" on multi-lane highways?

The roots of plants continue to grow throughout the life of the plant

A problem that has long plagued plant scientists is how a guiding gradient of proteins divides the construction phases among all the different specialized cell files (highway lanes) that exist in the roots

In the past 15 years, researchers from the Yrj Helariutta team at the University of Cambridge and the University of Helsinki have revealed the central role of cell-cell communication and complex feedback mechanisms involving blood vessel patterns

The Sainsbury/Helsinki team used single-cell RNA-seq and real-time imaging to analyze every step in the process of constructing a model plant Arabidopsis phloem cell file (sugar transport channel)

This is a mechanism that seems to help phloem cells mature quickly, using their own mechanism to explain maturation clues

The team also showed how the development of the phloem progresses gradually over time.

The co-leader of this work, Professor Yrj Helariutta, said that his team reconstructed the steps of Arabidopsis thaliana from birth to the final differentiation of the original phloem, revealing these steps

"By combining single-cell transcriptomics with in vivo imaging, we have mapped out the cellular events from the birth of phloem cells to the final differentiation into phloem sieve cells

The researchers plan to further explore the evolutionary process of these mechanisms and whether these steps can be replicated in other plants and other plant species
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Article title

Cell-by-cell dissection of phloem development links a maturation gradient to cell specialization